Interference Detection

Tom,

I just go surface to surface, a #10 screw and a #19 tapped hole are both .190 dia. Likewise with nuts/bolts, etc.

Dennis

Tom Chasteen wrote:

This is a big problem. One solution is to go to the configuration manager and use the selection tool hidden there to select all the hardware and suppress it. It isn't too hard to set up a rule to do this and then save it for future use.

There should be an > How do you guys handle fasteners when doing interference checking. I have

Create design tables of fasteners with the threaded sections cut away to match the minimum internal thread diameter. With this approach the interference detection will still recognize any interferences between the fastener nominal body (unthreaded surface) diameter and internal thread.

Not sure how this would be accomplished with Toolbox fasteners?

Kman

My current procedure in large assemblies is to insert a fastener group(assy w/ bolt, washers, and nut) in an appropriate subassy so that when all subassy's are mated, all fasteners are already installed. This prevents me from having to install fasteners forever. My last assy had over 1800 fasteners. Yet, I only inserted maybe 30 fastener groups into subassy's.

I try to have as few config's as possible. It seems to help reduce overhead and increase speed. That's why I've been boring out nuts and saving them.

I'll have to learn the advanced selection tool. That sounds like it may be a better option.

Tom

I wrote a macro that generates an Excel file that keeps a list of interferences that you want to ignore (two components plus the interference volume). So you end up with two lists -- valid interferences, and interferences you want to ignore. It's slower than the standard interference function, but overall it can be faster since you don't have to eliminate all spurious interferences. I haven't tried it yet with 2004. Drop me a line if you want me to email it.

Eric

Tom,

Assuming you are using design tables for fasteners. Modify the design table to cut away only the threaded surface of the screw to a diameter equal to or slightly smaller than the minor diameter of internal thread. There are screw tables that will give you the effective thread lengths of each size and length fastener. Now when you insert a fastener the only time you will receive an interference is if the unthreaded body of screw is making contact. And that is a good thing.

Kman

I have used that method in the past. Works very well, but I am not sure this could be incorporated with Toolbox.

Kman,

That is basically what I do now, except I drill out the nuts instead of changing the bolts. This way the nuts always measure the specified thread diam. (i.e. 1/4-20 unc).

I've been doing this for a while. I was just curious if there were better, or easier approaches.

SW always seems to have 90+% solutions. It's just that I wish we didn't have to always make up the rest of the percentage manually.

You would think that the guy doing the library and the guy doing interference detection would realize that they would eventually detect each other (1000's of times in a large assembly) and try to resolve their differences.

Tom

If SolidWoks ever comes up with a solution for this, I would hope they would have an option to increase the hole size rather than modify the screw size. Like you said, when you measure each, the size is obvious.

Maybe now that they have those bitmapped threads, they can use those in place of the hidden line cosmetic thread dealy.

Mike Wilson

Mike,

Understand, but what if one uses Hole Wizard for tapped holes?

Kman

Kman,

Good point, I add drill & tap notes to cover them. Not the best, but it works. SW still needs to address this issue so that we all don't have to develop our own work-arounds.

The only reason that I do it this way is that all measured sizes are the named thread size and as Mike said this makes things kind of obvious to others. Having the actual min and max thread diam's on the parts is accurate, but seems to cause more work than it prevents. I ,almost, always check for interferences just to prevent accidents.

Tom

Yeah, that would be nice. I wonder if an API program can be written to look for any Cosmetic Threads and place a hole there the same size and diameter as what the Cosmetic Thread actually calls out (without messing up the hole callout in the drawing)?

Another advantage to having the hole larger would be for the detection of a fastener that is too long in the case where you may have a blind tapped hole.

Here is an example of how a hole looks currently...